1. Field of the Invention
Embodiments of the inventive concepts relate generally to a semiconductor device. More particularly, embodiments of the inventive concepts relate to three-dimensional semiconductor memory devices having double cross point array and methods of fabricating the same.
2 . Description of the Related Art
To meet the demands of high-capacity and high-density semiconductor memory devices, there has been proposed a memory device having a three-dimensional cross-point array structure as described in U.S. Pat. No. 6,185,122 by Johnson et al. The memory device proposed by Johnson includes two or more memory layers of cross-point array, but the memory layers located at different levels are configured to share a bit line therebetween. Furthermore, three conductive lines are required to form two memory layers at different levels, but at least two thereof should be formed to be orthogonal to each other. According to this structure, processes for making memory cells or selection devices should be repeated for every memory layer. Moreover, in the case that three or more memory layers are stacked vertically, the memory device may suffer from an increase in disturbance between the memory layers and a decrease in operation margin.